Integrated circuit switches used in integrated circuits can be formed from solid state structures (e.g., transistors) or passive wires (MEMS). MEMS switches are typically employed because of their almost ideal isolation, which is a critical requirement for wireless radio applications where they are used for mode switching of power amplifiers (PAs) and their low insertion loss (e.g., resistance) at frequencies of 10 GHz and higher. MEMS switches can be used in a variety of applications, primarily analog and mixed signal applications. One such example is cellular telephone chips containing a power amplifier (PA) and circuitry tuned for each broadcast mode. Integrated switches on the chip would connect the PA to the appropriate circuitry so that one PA per mode is not required.
Depending on the particular application and engineering criteria, MEMS structures can come in many different forms. For example, MEMS can be realized in the form of a cantilever beam structure. In the cantilever structure, a cantilever arm (suspended electrode with one end fixed) is pulled toward a fixed electrode by application of an actuation voltage. The voltage required to pull the suspended electrode to the fixed electrode by electrostatic force is called pull-in voltage, which is dependent on several parameters including the length of the suspended electrode, spacing or gap between the suspended and fixed electrodes, and spring constant of the suspended electrode, which is a function of the materials and their thickness. Alternatively, the MEMS beam could be a bridge structure, where both ends are fixed.
However, as semiconductors become smaller, due to scaling, several issues can arise in the MEMS. For instance, silicon scaling leads to smaller ratios of power required to turn on and turn off semiconductor devices, which results in power being transferred through semiconductor devices when power should not be transferred, e.g., when the semiconductor devices are turned off. This is evidenced by off currents in semiconductor devices being measurable. Moreover, silicon scaling makes it more difficult and more costly to radiation harden semiconductor devices on chips, especially when there are many devices and each of the devices are extremely small.
Accordingly, there exists a need in the art to overcome the deficiencies and limitations described hereinabove.